I ordered some replacement parts from Bob Roberts (see the link to his web site on my Robotron 2084 links page), I will be trying to undertake the replacement of the 5114 CMOS RAM chip, which I suspect is shot on the CPU board in the machine now.
Also, in my 10 minute Robotron challenge, I just scored 905,875 points and reached wave 30. Yeah, I know, I my skills are still super rusty.